Back in the Underground
by ItsKpex
Summary: One moment, Steven was finally happy living on the surface with his friends, but now, Frisk had reset the timeline. But, something's different this time around. Somehow, Steven is thrown into the world that is the underground, and is given the task to stop a certain knife-wielding child from killing everyone he has come to love. [Sequel to Life on the Surface] [T for Language]
1. Chapter 1

My eyes fluttered open, the only thing that was in my field of view was a giant hole with light beaming through it. I quickly picked myself of the ground, terrified at my current surroundings. A million questions swarmed my mind. 'Where am I? How did I get here? Am I dead? Am I dreaming?' I pinched myself to make sure if I was dreaming, but I still remained awake. I couldn't see too well in this place, but I could make out a door on the opposite side from me. I hesitantly started walking towards it. I looked around cautiously, making sure that I was safe.

"H-hello? Anyone?" I said shakily, my whole body seeming to tremble.

"Is someone there?" I heard a woman's voice say from the door. I froze in place, the voice sounding slightly familiar. Suddenly, Toriel appeared in the doorway, a shocked expression on her face.

"Oh dear, another human? That has been the second one that has fallen here." She said. Wait, human? Does she not remember me?

"W-Where are we?" I asked her, and she smiled at me.

"You are in the underground, my child. I am Toriel." She explained. The UNDERGROUND? How am I here?

"Do you know who I am?" I asked her, hoping that her answer would be yes. She shook her head, and I nearly passed out. It suddenly clicked in my mind. Sans had told me about alternate timelines and Frisk's ability to reset the timeline. But that didn't explain how I'm here.

"Child, are you alright? You seem lost in thought." Toriel asked me, seeming genuinely worried. I snapped out of my daze, coming back to reality. I have to find Sans, he has to know what's going on.

"Sorry for being rude, but I need to leave I have to go home." I told her, and she looked saddened as those words left my lips.

"I was afraid you would say that. If that is what you wish, I will show you the way out." Toriel told me, which made me sigh in relief. She motioned me to follow her. We trekked through various rooms filled with puzzles, Toriel helping me solve them along the way. One thing that I noticed that there was grey dust piles in some of the rooms, which made Toriel seem to look totally distraught.

"Um, what happened? Toriel?" I asked her, and she looked at me worriedly.

"Cmon, child. We must hurry!" She grabbed my hand and practically dragged me off towards where I presumed was the exit.

"What's wrong?" I asked her, trying not to trip and face plant into the ground.

"I left the other child alone at my home, she was sleeping when I left. I think she killed all those poor monsters back there! She might have went through the door to the rest of the underground!" Toriel explained, which completely shocked me. Frisk killed those monsters? That has to be a lie, she couldn't do that, I know it. We ran until we reached what seemed to be her home, which was made out of purple bricks. We entered the home, which had a massive staircase that seemed to lead down into some sort of basement. Toriel ran down the stairs, her purple dress flowing behind her. I ran after her, running so fast that I almost tripped down the stairs. I saw her at the turn of the corridor, looking straight ahead in fear. When I reached where Toriel was standing, I followed to where her gaze was. A door was left wide open, revealing a snowy forest with a bitter cold wind blowing through the doorway.

"Oh no, she's gone! She's out there! Oh dear, oh dear! My child, you have to stop her!" Toriel grabbed my shoulders, forcing me to look at her.

"Wha-? Me? How?" I stuttered, not sure if I could handle stopping a girl who killed about a dozen monsters, and who knows how many more now.

"I know you can, my child. You are our only hope! Please hurry!" Toriel cried, tears rolling down her face. I nodded and darted out through the doorway, ignoring the icy wind battering against my skin. I had to find Sans, he has to know! He just has to! I kept running, snow clinging to my shoes, making them feel numb. I noticed more piles of dust on the side of the path I was running on, which only made me run faster. I wasn't watching where I was going, and stepped in a pile of dust, the grey substance coating my left sneaker. If I ate anything, I would've puked it up right now. I started dry heaving, trying not to look at my sneaker. I knew I had to keep moving, I couldn't let anything happen. I kept running, despite my lungs burning from the exercise. I ran over a wooden bridge with some bars over it, seeing what looked to be a sentry station...AND SANS! I ran as fast as I could, the station getting closer to me by the second. As I reached the station, I noticed that Sans was sleeping. I went up to the sleeping skeleton and shook him awake.

"Sans! Sans, wake up man!" I yelled at him, which made him open his eyes groggily. When he realized that it was me, his eyes widened in disbelief.

"St-Steven?" He stuttered. Oh thank god, he remembers me. I pulled him into an embrace, and he gladly wrapped his arms around me as well. "Oh god, I thought I'd never see you again. How are you here?"

"I'll explain later, we have to stop Frisk! She's killing everyone!" I said anxiously, wanting to get moving.

"Wait, what! I left the kid with Papyrus to do his puzzles!" Sans put his hands on his head in distress.

"Cmon! We have to find her!" I yelled, almost in tears. Sans held out his hand, which I took quickly. I felt my body pop out of existence for a second before reappearing at what looked to be a shiny metal floor. Sans groaned and teleported us to another puzzle, which was empty as well. Finally, Sans teleported us to a semi-large wooden house which was located in a small town.

"You check if they're in there, I'll check the rest of the town!" Sans told me and I nodded. I burst through the front door of the house, looking around frantically.

"Papyrus!" I yelled out, but no answer came. I looked into the kitchen, only to find it empty except a lone plate of spaghetti on the table. I sighed and darted up the stairs, flinging the first door open wide open, revealing Papyrus's room. It seemed similar to his room on the surface, the red car bed, the action figures, the computer, all the same. I shook the memory of the surface, knowing that timeline was gone now. I ran out of Papyrus's room, heading towards the other room upstairs, which I presumed was Sans'. I turned the door handle, but it was locked. I pounded on the door just to make sure.

"Papyrus!" I yelled through the door, but silence was the answer I got. I rushed down the stairs and ran towards the door. I tripped and slid on my knees, getting rug burn on both of them. Ignoring the burning sensation. I ran back out into the cold, the air slightly soothing my burning knees. Sans appeared in front of me, looking exhausted and sweating profusely.

"I...didn't...find him...anywhere!" Sans tried to catch his breath, probably from all of the frequent teleporting. I looked behind him, and I could make out a tall silhouette in the fog. My eyes widened in horror. Sans looked at me with a confused expression. "Steven? What's-" I didn't let him finish his sentence. I started sprinting into the fog, trying to reach the silhouette in time. I got closer and closer, I could definitely tell that it was Papyrus. Even closer, I saw that Frisk was in front of him. I got close enough to them to see that Papyrus had his arms outstretched, offering the smaller child mercy. What he'd fail to notice was the sharp, dust covered knife behind her back. I knew what her plan was. Frisk lunged at Papyrus, the blade coming for him...

...but it didn't hit him.

...

~woo! Sequel! Anyway, this was the idea I had for a sequel to my previous story. I think it's a good idea, but I want to hear what you guys think. As always, feedback is appreciated. Thanks!


	2. Chapter 2

Everything went by in a blur, the one moment I saw Frisk lunge at Papyrus, the next, I felt a very sharp pain in my shoulder. Suddenly, I felt my surroundings focus, I was standing in front of Papyrus, Frisk looking at me with pure hatred. But, her eyes weren't her usual chocolate brown, but were a deep shade of red, almost like blood. I looked to my right shoulder to see that the knife was jabbed into my shoulder. Surprisingly, I wasn't screaming, or crying, which was odd. I have a low pain threshold, which meant I would be screaming or crying right about now, but I wasn't. I mean, it still hurt, but not as much. Grimacing at the blood slowly trickling out of my wound, I turned my attention back to Frisk, who scoffed at me.

"A-ANOTHER HUMAN?" Papyrus exclaimed in surprise, which I could see why. I literally ran from out of no where and took the bullet for him, well, stab wound actually. Frisk, grinning with an evil smile, yanked the knife out of my shoulder, which caused me to yelp in pain. Her grin got wider when she saw that I was in pain.

"Well well well, if it isn't the one and only Steven Durkin. I didn't expect to see your dumb ass here" Frisk said, her voice layered and having a slight demonic tone to it.

"F-Frisk? What're you do-" I was cut off by her laughing with an evil laugh.

"Oh, I'm not Frisk, far from her. I'm keeping her captive in her own body, forcing her to watch all of her dearest friends get murdered. But, now that you're here, I need to come up with a new plan. You've bought you and your friends some time, but I'll be back, and I'll kill you all! HAHAHAHAHA!" She cackled loudly, running off into the fog, her silhouette getting smaller and smaller. I sighed, holding my hand to my bleeding stab wound. Suddenly, I saw a smaller figure starting to approach us. The figure got closer and closer, and I recognized it as Sans. Gasping for air, he looked significantly relieved when he saw that Papyrus was okay.

"Oh, Paps! You're okay!" Sans hugged his brother, who returned the hug.

"THANKS TO THIS OTHER HUMAN, THE GREAT PAPYRUS IS FINE. BY THE WAY, OTHER HUMAN, I DON'T BELIEVE I RECOGNIZE YOU!" Papyrus gave me a kind smile, but I could do everything but that. He...doesn't remember me? I looked at Sans, tears forming in my eyes, and he gave me a sympathetic look. I looked back at Papyrus, whose smile changed to a confused frown.

"Paps, you don't remember me, do you?" I said, my voice sounding broken and quiet.

"YOUR NAME SOUNDED QUITE FAMILIAR, BUT I DO NOT BELIEVE WE HAVE MET BEFORE!" Papyrus answered, scratching the back of his skull. I frowned, starting to feel the adrenaline begin to subside, the pain in my shoulder getting more and more strong. Sans must've seen me grimace at the pain, since he walked up to me and put his arm around my shoulders.

"Cmon, kid. Let's fix you up." Sans said, to which I nodded in reply. We walked to Sans and Papyrus's house, since Sans was pretty much 'bone tired', as he said, to teleport the three of us. I stared at the snow covering the ground, the crunching of our feet was the only thing I could hear at the moment. How could Papyrus not remember me, after all we went through? Was I not a good enough friend to him? Did I do something wrong? Sans must have sensed my distress, since he tightened the grip he had around my shoulders, in an attempt to comfort me. I sighed and continued walking, looking at the ground still. After about another couple minutes of walking, we finally made it back to the skelebros' house.

"Hey, Paps. Can you go get some cinnamon bunnies at the shop? I think the kid might need 'em." Sans asked the taller skeleton.

"THE GREAT PAPYRUS HAS GOT THIS!" Papyrus declared before running off in the direction towards the shop. I couldn't help but chuckle a little, Papyrus was still the same person. Sans escorted me inside his home, motioning me to sit at the couch.

"I'm gonna look for some bandages." Sans said, going off into the kitchen. I wondered why he didn't look in the bathroom, but then I realized something. They don't have one...how do they pee? See, these are the important questions. I laughed a little before I saw Sans return with nothing in his hands.

"Yeah, I didn't think we had bandages since we're, y'know, skeletons. That's why I sent Paps to the shop." Sans explained, plopping down next to me on the couch. "Anyway, are you okay? You seemed pretty upset when we were walking here." Sans asked me with concern, the sadness and confusion hit me like a ton of bricks. I sighed and looked at him.

"Does Paps not remember me because I wasn't a good enough friend to him? Did I do something wrong?" I then started to look at the cyan and purple striped carpet of the room. I felt Sans pull me into a hug, which comforted me a little, but I was still worried.

"No, it's not that! I only remembered you because I know about the different timelines, but Papyrus doesn't. It might take a lot for him to remember you." Sans explained, and I relaxed a little more. I broke the embrace, still feeling crummy.

"I just want him to remember me..." I trailed off, tears starting to blur my vision. I heard Sans sigh and start rubbing my back.

"It's okay, we'll find a way," Sans said to me, and I nodded. I heard Papyrus open the front door, which caused me to quickly wipe away the tears.

"BROTHER, HUMAN #2, I AM BACK!" Papyrus proclaimed, Sans stood up and walked over to Papyrus, taking the bag from him.

"Thanks bro, you're the best." Sans thanked Papyrus, which made Papyrus smile. Sans pulled out what looked to be a cinnamon roll and handed it to me. "Here kid, eat this." Sans said to me, and I looked at him with a confused expression. He just nodded and gestured to the pastry. I shrugged and ate the cinnamon 'bunny'. I felt the wound on my shoulder close up, which caused me to shudder at the feeling. How did that heal me like that? I looked at Sans, who was smiling at me.

"How the hell did that actually work?!" I was utterly confused at what magic or whatever did this.

"You okay, kid?" Sans asked me, and I nodded, suddenly having a lot of energy.

"I'M GLAD YOU ARE OKAY, HUMAN!" Papyrus told me, which I appreciated, but I still was sad about him not remembering me. I sighed and just looked at the ground, thinking if I could make him remember me at all. Suddenly, an idea appeared in my mind. I stood up and walked over to Sans.

"I have an idea to get Papyrus to remember, can we go somewhere more private?" I whispered to Sans, and he nodded in understanding.

"Hey Paps, the kid and I are going out for a bit, okay?" Sans looked at Papyrus, who had a confused expression.

"WHERE ARE YOU TWO GOING?" He asked us, and I looked at Sans, not knowing what to say.

"Just to take a walk. We'll be back soon." Sans said before grabbing my hand and teleporting us to his sentry station in the forest. He leaned against the small wooden structure, looking at me with curiosity.

"Shoot." He told me.

"Okay, did Paps have a favorite song that he heard me sing? Maybe if I sang it, he'll remember." I told him, and Sans was deep in thought for a second.

"I can't remember the name, but it was the song that had a lot of humming in it." Sans told me, the name clicked.

"Please Don't Go by Joel Adams? I love that song! I cried when I first heard...it...I never said that. I remember how to sing that, it's perfect." I said, getting excited. I heard Sans stifle a laugh, and I glared at him.

"You cried?" Sans then burst out laughing, holding his stomach. I turned as red as an apple, trying to get him to teleport us back.

"Sans, cmon. It's not funny!" I yelled, crossing my arms. Sans started to calm down, his laugh attack now a light chuckle.

"Alright, alright, I'm sorry okay?" Sans said, still having a smile on his face.

"Yeah, yeah, let's go." I told him, and he held out his hand, getting ready to teleport us back. I blinked and I was back in Sans and Papyrus's house. Papyrus can be heard in the kitchen, pots and pans banging, something sizzling on the stove.

"Yo Papyrus!" Sans yelled into the kitchen, causing a startled scream from Papyrus to ring out, pots and pans clashing to the ground.

"THE GREAT PAPYRUS IS OKAY! Owie." Papyrus said from the kitchen, causing me to look at Sans, concern in his expression.

"I'll go check on him, make sure he didn't rattle his bones to much." Sans smirked and walked into the kitchen, Papyrus letting out an annoyed sigh. I just nodded and stood there, getting deeper in my thoughts. I hope that this works, I really do. Besides Sans, Papyrus is the only other monster I know well here, and I need all the help I can get. Stopping a cold blooded killer inside your brother's future crush's body is not that simple. We don't even know how much time we have before she comes back, but I can't focus on that, I'll probably have a panic attack.

"WHAT DOES THE HUMAN WANT TO SHOW ME?" Papyrus asked curiously, which broke me from my thoughts.

"Just listen," Sans nudged his brother before looking at me and nodding.

"I know you don't remember me, but maybe this song will jog your memory." I said, clearing my throat. I started humming the beat, closing my eyes. I started to sway with the beat, getting into the song.

 _'Nobody ever knows_

 _Nobody ever sees_

 _I left my soul_

 _Back there now I'm too weak_

 _Most nights I pray for you to come home_

 _Praying to the Lord_

 _Praying for my soul_

 _Now please don't go_

 _Most nights I hardly sleep when I'm alone_

 _Now please don't go, oh no_

 _I think of you whenever I'm alone_

 _So please don't go'_

I looked at Papyrus, who had tears in his eyes. I think it's working!

 _'Cause I don't ever want to know_

 _Don't ever want to see things change_

 _Cause when I'm living on my own_

 _I'll wanna take it back and start again_

 _Most nights I pray for you to come home_

 _Praying to the Lord_

 _Praying for my soul_

 _Now please don't go_

 _Most nights I hardly sleep when I'm alone_

 _Now please don't go, oh no_

 _I think of you whenever I'm alone_

 _So please don't go_

 _I send so many messages you don't reply!_

 _I gotta figure out what am I missing babe!_

 _Singing now_

 _And I need you now, I need your love!_

 _Now please don't go_

 _Most nights I hardly sleep when I'm alone_

 _Now please don't go, oh no_

 _I think of you whenever I'm alone_

 _So Please Don't_

 _Please don't go_

 _Please don't go_

 _Please don't go_

 _Please don't go_

 _I think of you whenever I'm alone_

 _So please don't go'_

Humming the last part of the song, I looked at Papyrus, who still had orange tears in his eye sockets, but he was smiling. Did it work?

"Paps?" I asked nervously hoping that he remembered.

"S-Steven? I...remember. This was my favorite song I heard you sing." Papyrus said, his tone quiet. Oh my god, he remembered, he actually remembered. I couldn't help but run up to him and hug him. I felt him return the hug, which made me smile.

"How did I ever forget you?" Papyrus said, hugging me tighter. I looked up at him and smiled, and he returned it. I broke the embrace, and I looked at Sans, who had blue tears in the corners of eye sockets.

"And you made fun of me for crying." I smirked at Sans.

"No, I just have...sweaty eyes?" Sans said, though it sounded more like a question. Me and Papyrus just laughed and Papyrus walked up to him and hugged him.

"COME ON BROTHER, STEVEN, I THINK WE DESERVE SOME SLEEP, WE HAVE HAD A LONG DAY!" Papyrus declared, and I nodded in agreement.

"Yeah, I'm super tired right now." I said sitting on the couch.

"Hey Paps, do you still want me to read you a bedtime story?" Sans asked his brother, who nodded vigorously. "Alright, let's go bro." Sans said, and they both started walking up the stairs. I yelled a good night to them, and they disappeared into Papyrus's room. Sans managed to turn off the lights downstairs where I was, so I was engulfed in darkness. I laid down on the couch and tried to sleep, but haunting thoughts kept coming to my mind. Frisk, or whoever that is now, can be anywhere! She could kill me right now! Can she see me, does she know I'm here? My heartbeat increased, my breathing started to become short. I stopped myself and started to take deep breaths, ultimately stopping my panic attack. I looked around the room cautiously, hoping not to find a knife wielding maniac demon child. I heard a door open upstairs, which made me jump in fear. I peered over the back of the couch and upstairs, and saw the outline of what I think is Sans. He walked towards his room and entered it, and I heard a clicking sound come from the door, meaning he locked it. I couldn't sleep down here, so I did the only thing I could. I stood up, my legs shaking like noodles. I made my way up the stairs carefully, making sure I don't trip and fall down them. I walked to his bedroom and knocked on the wooden door.

"S-Sans?" I stuttered, my voice sounding broken and fearful. I heard some shuffling from behind the door, soon after I heard a click and the door opened, revealing a half confused and half concerned Sans.

"Kid, you okay?" Sans asked me.

"C-can I sleep in your room? I'm just scared that Frisk, or whatever possessed her, would try to kill me in my sleep." I told him and his eye sockets widened.

"Oh, okay, but I'll never let that happen to you." Sans motioned me to come in and I entered the dark room. Sans went over to his bed and I scanned the room for a possible place to lie down. I settled for next to the bed, and I sat down there.

"Y'know you could sleep up here with me, if you want." Sans told me.

"Are you sure?" I asked him, and he nodded. I stood up and climbed into the bed, a sudden feeling of security washing over me. I smiled and snuggled closer to the covers. I felt Sans put his arm over me, which made me feel safer. I moved closer to him, and I felt the warmth radiating off of his body, which I was still confused about, since he's a skeleton. That only helped me fall asleep more, since I was able to drift off into a peaceful slumber.

...

~Hey guys! Hoped you liked this chapter! Also, I'm able to read reviews again, so post a review if you want to give feedback, it's always appreciated. Anyway, thanks for reading.


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